The external circulation technology of raw material roller mill is a new stage in the development of roller mill system. The external circulation reform of the raw material roller mill system can save energy remarkably. After the external circulation reform, the power consumption of the raw mill system is comparable to that of the raw material final grinding system of the roller press. The reform of external circulation roller mill of raw material final grinding system can retain the equipment and foundation of the original roller mill. Compared with modification of the raw material final grinding system with the new roller press, it can save about half of the investment and reach the energy consumption index equivalent to that of the raw material final grinding system of the  roller press. In 2018, Tianjin Cement Industry Design & Research Institute Co., Ltd. carried out two projects. Practice shows that this kind of modification can improve the system output, reduce raw mill fineness, and reduce the power consumption of the raw mill system by 4kWh/t compared with that before the external circulation reform.